Working cylinder with integral cylinder head



Nov. 22, 1955 2,724,368

W. E. MILLER WORKING CYLINDER WITH INTEGRAL CYLINDER HEAD Filed Oct. 20, 1952 hwozu f. MLLER JNVENTOR.

United States Patent Ofiice WORKING CYLINDER WITH INTEGRAL CYLINDER HEAD Wendell E. Miller, Hutchinson, KansL, assignor to The Cessna Aircraft Company, Wichita, Kans., a corporation of Kansas Application October 20, 1952, Serial No. 315,611

9 Claims. (Cl. 121-38) This invention relates generally to a displacement type fluid pressure operated jack, press, or what is commonly called a working cylinder or actuator. More particularly the invention relates to a highly simplified construction for such actuator units.

It is the chief object of the invention to provide a construction which eliminates the need for providing a removable cylinder head for the cylinder or barrel portion of such a unit, thus eliminating the problem of pressure sealing between the head and barrel, and also greatly reducing the cost of fabrication and assembly.

It is a more specific object to provide a new construction for a working cylinder unit which permits the entire cylinder proper to be cast or otherwise formed in a single piece if desired, or which optionally permits the head and barrel to be made separately and welded permanently to each other before the plunger is installed.

It is an additional object to provide a new construction for a working cylinder unit which reduces machining to a minimum during fabricaton of the cylinder or barrel proper, thus greatly reducng the cost of manufacture of the entire unit.

The invention, together withother objects attending its production will be more clearly understood when the following description is read in connection with the accompanying drawings, in which i l Fig. 1 is a longitudinal sectional view through a working cylinder unit or jack embodying the invention;

Fig. 2 is a plan vew of la snap ring used as a part of the unit illustrated;

Fig. 3 is a view similar to Fig. 1 illustrating one means of dis-assembling the unit;

Fig. 4 is a fragmentary view, showing detailsin con struction and the first step in assembly of the unit;

Fig. 5 is a longitudinal sectional view illustrating, the second step in assembly; a

Fig. 6 is a fragmentary longitudinal sectional view illus' trating the final step in assembly of the unit; and

Fig. 7 is a fragmentary sectional view illustrating the invention in different form.

Referring to the drawings, the numeral 10 designates a cylinder or barrel as a whole, thenumeral 11 designates a plunger as a whole, thenumeral 12 designates a plunger travel limiting means, in the embodiments shown a snap ring, and the numeral 13 designates a fitting for connecting the cylinder to a source of fluid pressure.

The cylinder 10, in the embodiment illustrated in Figs. 1 to 6, is shown as a one piece casting having one closed end or head 14 and a reduced diameter elongated plunger aperture 15 (Fig. 4) at its opposite end. This aperture 15 and an aligned internal recess16 head 14 are machined at the same time and with the same tool. They are therefore identical in diameter, and both are of a size to slidably but snugly receive plunger 11.

The major portion of the cylinder bore17 is larger in diameter than aperture 15. This bore 17 has a concentric portion 18 of reduced diameter located immediately adja cent the inner end of aperture 15 and concentric with re- Patented Nov. 22, 1955 tudinally disposed lug 19 which serves as a means for free ends, plunger 11 is forced in an outward direction anchoring the cylinder to a fixed support or to a work part to be oscillated or reciprocated. Adjacent head 14 the cylinder wall is provided with a threaded aperture 20 (Fig. 5) for receiving pressure fluid fitting 13. It should be noted that the threading of this aperture 20, the ma chining of aperture 15 and recess 16, and the machining of annular sealing ring groove 21 are the only machine work operations required in fabricating such a cylinder. Groove 21 houses a neoprene 01*"other composition sealing ring 22 which is compressed therein by plunger 11, and which thus prevents leakage of pressure fluid through aperture 15 during plunger reciprocation.

Plunger 11 is of constant diameter substantially throughout its length. At its outer end it is flattened, as shown, and laterally perforated at 23 for connection to a Work part to be moved. Nearits inner end this plunger is provided with an annular groove 24 for receiving and holding snap ring 12. At its extreme inner end plunger 11 is chamfered to provide an annular wedging surface which facilitates forcing the ring over that end of the plunger and into its groove 24.

Assembly Fig. 4 illustrates the first step in assembling the described actuator after fabrication of its individual parts. It will be noted from Fig. 4 that snap ring 12 has a sector removed, approximately one fourth, to reduce its minimum lateral measurement it will also be noted that this minimum lateral dimension is just slightly smaller than the diameter of aperture 15. The first step in assembly, then, is to insert the snap ring into the interior of the cylinder 10. Next, the cylinder is turned to an upright position with the open end down. The cylinder is shaken slightly to seat snap ring 12 in bore portion 18, as shown in Fig. 5. The chamfered end of plunger 11 is inserted through aperture 15 so that the ring 12 seats on the chamfer. By maintaining the upright position of the cylinder and pushing plunger 11 inwardly, ring 12.is carried by the chamfered end of the plunger into contact with shoulder 25 surrounding recess 16, as clearly shown in Fig. 6. The plunger is next forced into recess 16 and during such movement the chamfered surface forces ring 12 over the plunger end and into groove 24. Thereafter ring 12 contacts the outer end of bore portion 18 to limit.

Dis-assembly To disassemble the described actuator, fitting 13 is removed from the cylinder and a thread protector fitting 26 is substituted. A steel pin 27 is then inserted through the bore of fitting 26 until the inner end of the pin rests on plunger 11, as clearly shown in Fig. 3. With the inner end of pin 27 in contact with the ring 12 near one of its while the inner end of pin 27 is simultaneously heldagainst the surface of the piston; The pin contacted end of ring 12 is thus forced out of its groove, and the entire ring is literally pulled oil the end of the plunger and drops free in the cylinder. The plunger may be entirely removed from the cylinder and O-ring seal 22 replaced if desired.

Fig. 7 illustrates a slightly different embodiment of the invention. The primary difference is that the cylinder 30 is made separate from cylinder head 34, and the two are secured together, as by welding, indicated at 35. In addition, the plunger 31 is provided with a plurality of spaced annular grooves 32 and 33 for seating snap ring 36. Also the recess 36 in cylinder head 34 is of slightly greater depth longitudinally than the distance between the inner end of plunger 37 and that ring groove most remote from the inner end of the plunger. The operation, assembly, and disassembly are the same as for the embodiment illustrated in Figs. 1 to 6. The steel pin 27 is used to move the snap ring from the groove 32 to the groove 33, and vice versa. The travel limit of the plunger may be varied by positioning the snap ring in a desired one of said grooves.

Having'described the invention with sufficient clarity to enable those familiar with this art to construct and use it, I claim:

1. A hydraulic actuator comprising: a unitary cylinder having a fixed head at one end and a reduced diameter plunger aperture at its opposite end; a fluid port in the cylinder wall; a plunger reciprocable with relation to said cylinder through said aperture; an internal recess in said head of a size and shape to slidably and snugly receive said plunger longitudinally; an annular circumferential groove in that portion of the plunger which is adapted to reciprocate within the cylinder; and a snap ring carried in said groove to limit the movement of the plunger in both directions, said snap ring being larger in external diameter than the respective diameters of both the plunger aperture and the head recess, and having a sector removed to reduce its minimum lateral dimension to a measurement less than the plunger aperture in the cylinder.

2. The ram described in claim 1 in which the extreme inner end of the plunger is chamfered to facilitate mounting of the snap ring.

3. A fluid pressure operated actuator comprising: a one piece cylinder having an integral internally recessed head at one end and a reduced diameter open longitudinally dis-- posed cylindrical plunger aperture at its other end; a port for pressure fluid through the Wall of said cylinder; a plunger reciprocable in said aperture and extending into the interior of said cylinder, the recess in said head being of a size and shape to complementally and slidably receive the inner end of said plunger; an annular groove adjacent the inner end of said plunger; and a snap ring carried in said groove and serving to limit the movement of the plunger with relation to the cylinder, said snap ring being slightly larger in external diameter than the respective diameters of both the plunger aperture and the head recess, and having a sector removed to reduce its minimum lateral dimension to a measurement less than the diameter of the plunger aperture in the end of the cylinder.

4. A displacement type fluid pressure operated jack or actuator comprising a cylinder having a non-removable fixed head closing one end and having a reduced diameter elongated plunger aperture at its opposite end, the major remaining portion of its borebeing of larger diameter than said plunger aperture; a plunger of constant diameter projecting into said cylinder and reciprocable through said aperture; a fluid pressure port communicating with the interior of said cylinder; an annular snap ring seating groove near the cylinder enclosed end of the plunger; and a snap ring of larger outside diameter than said plunger and of smaller outside diameter than the bore in said cylinder seated in the groove, whereby the snap ring limits the outward travel of the plunger with relation to the cylinder, and does not contact the wall of the cylinder bore during plunger reciprocation.

5. The actuator described in claim 4, and an internal recess inthe cylinder head of a size and shape to slidably and snugly receive the grooved end of said plunger, the circumferential shoulder surrounding the entrance of said recess serving to force the snap ring over the grooved end of the plunger and into its groove seat as the inner end of the plunger is moved into said recess.

6. The actuator described in claim 5 in which the inner grooved end of said plunger is chamfered to aid in initially positioning the snap ring on the plunger end so that the ring may be forced around the plunger and into its groove seat as the plunger end moves into said recess.

7. A longitudinally extensible hydraulic actuator of the displacement type characterized by a cylinder having a permanently closed end and an opposite longitudinally apertured end, the aperture being of cylindrical shape and of substantially smaller diameter than the remaining portion of the interior of the cylinder; an inlet port in the cylinder wall for hydraulic fluid; an elongated plunger of substantially constant diameter extendin reciprocably through .said aperture into the interior of said cylinder; and removable means projecting outward from the pe riphery of the cylinder enclosed portion of said plunger and into the larger diameter bore of the cylinder for limiting outward movement of the plunger through said aperture, said means terminating short of contact with the surface of the cylinder bore so that there is no frictional contact between the two during plunger reciprocation, and fluid may freely enter the space between the plunger and the cylinder wall.

8. A single acting hydraulic actuator of the displace ment type characterized by a single unitary one piece cylinder having a head closing one end which is integral with the cylinder Wall; a longitudinally disposed cylindrical aperture in the opposite end of said cylinder, said aperture being of smaller diameter than the interior diameter of the cylinder; an elongated plunger of substantially constant diameter reciprocable longitudinally through said aperture; means sealing between the surface of said aperture and the adjacent surface of the plunger; and removable means projecting outward from the periphery of the cylinder enclosed portion of said plunger and into the larger diameter bore of the cylinder for limiting outward movement of the plunger through said aperture, said means terminating short of contact with the surface of the cylinder bore so that there is no frictional contact between the two during plunger reciprocation, and fluid may freely enter the space between the plunger and the cylinder Wall.

9. A hydraulic actuator comprising: a unitary cylinder having a fixed non-removable head at one end and a plunger aperture of smaller diameter than the interior diameter of the cylinder at its other end; a plunger of substantially constant diameter mounted in said aperture for reciprocation in the cylinder; a circumferential groove near the'cyli'nder enclosed end of said plunger; and a snap ring carried in said groove to limit the outward movement of saidplunger, said snap ring being larger in ex ternal diameter than thediameter of said plunger and having a sector removed to reduce its minimum lateral dimension to a measurement less than the diameter of said aperture.

References Cited in the file of this patent UNITED STATES PATENTS 

